Hydraulic jack



D. E. HENNESSY.

HYDRAULIC JAK. APPLICATION FILED JUNE 23, I914- RENEWED OCT-3,1917.

1,327,470. Patented Jan 1. 6,1920.

2 SHEETS-SHEET l- UNITED STATES OFFICE.

DANIEL E. F HOLYOKE, MASSACHUSETTS, ASSIGNOR T0 HERBERT W. COWAN, J. LEWIS WYCKOFF, AND EDWARD N. WHITE, TRUSTEES, DOING BUSI- NESS AS COWAN TRUCK COMPANY.

HYDRAULIC JACK.

Specification of Letters Patent.

Application filed f une 23, 1914, Serial No. 846,731. Renewed October 3, 1917. Serial-No. 194,591.

To all whom'it may concern:

Be it known that I, DANIEL E. HnNnnssY, a citizen of the United States, reslding at Holyoke, county of Hampden, and State of Massachusetts, have invented certain new and useful Improvements in Hydraulic Jacks, of-which the following is a clear, full, and exact description. 1

This invention relates to elevating devices such as elevating-trucks, and has for one of its objects improved means for shutting off the action of the intermittently operable mechanism, such as a fluid-operated jack,

when the platform is sufficiently ra1s ed.- Other objects of the invention are to provide a-simple, practical and efficient device of the class described.

These being. among the objects of the present invention, the same consists of cer-. tain features of construction and combina tions of parts to be hereinafter described and then claimed with reference to the accompanying drawings illustrating suitable embodiments of the invention, and which- Figure 1 is a plan view; 7

Fig. 2' is an enlarged transverse section on the line 14 Fig. 1; n

Fig. 3 is an enlarged longitudinal section of the preferred pump and jack; J

Fig. 4 is an enlarged detail section of a relief valve mechanism;

Fig. 5 is a transverse section on the; line 77 Fig. 3; a

Fig, 6 is a broken detail section of the pump and jack taken at rlght angles to Fig. is a side elevation of the pump and a part of the jack; and

Fig. Sis an enlarged transverse section partly in elevation on line 1010 Fig. 1,

showing the preferred relief valve actuator.

Referring to-Fig. 1, the base 10 of the truck is provided with rear wheels 11 and affront caster wheel 12, which is supported in a frame 13 by means of an .axle pin.

Said caster frame is provided with'a vertical swivel pin 15 'which journals in a suitable bearing 16 in a bracket 17. extending constitute an operating lever fora upwardly and forwardly from the base 10. Means for moving the truck comprise a tongue or handle, which also is adapted to P 1 1 and is provided with bifurcations 19 which are perforated to receive the-ends of the axle pin upon which the said tongue may be swung vertically. The platform 20 of the wardly relatively to the base, but in'the preferred form of the present invention the platform is adapted to be raised through the application of power whichis so applied throu h the intervention of suitable mechanism etween the base and the platform, that the platform is elevated and at the same time the base and latform are shifted longitudinally relative y to each other. Any suitable means may be used for this purpose, a detailed illustration of this .means not being essential to an understanding of the invention.

Suitable power means are more particularly shown in Figs. 3 to 7 inclusive.- A pump 25 and a fluid-operated jack 26 are the main parts involved in connection with the illustrated power mechanism. 1 Said pump is provided with a cylinder 27, which at its front end is provided withv lateral bearing sockets 28, 28, which receive suitable pivot pins 29, 29 rigidly mounted on the front portion of the base as shown in Fig. 1. The piston 30, which reciprocates in the cylinder 27 may be operated in any suitable manner, but preferably by means of the handle of the truck. To this end the said piston 30 is pivotally connected by a link 31 to a lever 32, which is pivoted to the extension 17 of the base, the upper end of said lever carrying a link 34. The link 34 is provided with a recessed keeper, which is adapted to be en aged with. a pin on the truck handle. Vhen the handle is free from said keeper the truck may be steered thereby, but when it, is engaged with said keeper the piston 30 of the pump may be reciprocated by the oscillation of said handle, which-serves as a hand lever. To prevent injury to the pump from too great strokes of the operating handle, particularly as the jack swings about the pivots 29,

the lever 32 is provided with stops 33 which engage parts of the frame and limit the movements of said lever in both directions.

At the rear end of the pump cylinder 27 is a head 37, which is in common with, and also serves as a head for, the jack 26.

The jack 26 comprisesaram cylinder 38, which is provided with a screw connection with the head 37 at 39, a ram 40 operating in said cylinder, and a fluid supply chamber 41, which may be formed by'a cylindrical shell 42 placed outside of the ram cylinder, and a nut 43 having a screw connection at 44 with said ram cylinder. As shown in Fig. 1, the said ram is pivotally connected at 45 with the rear end of the platform 20. The object of the ram and pump is to produce, by areciprocation of the pump piston 30, an intermittent advancin motion of the ram 40, and thereby apply lifting power to the platform to enable the latter to be directed upwardly by the co-acting inclined members before mentioned.

As shown more fully in Fig. 6,, the common head 37 for the pump and jack is provided with a passage 46 leading from the supply chamber 41 to the pump cylinder 27. A portion 47 of this passage extends axially through the head 37. Said passage 46 is controlled by means of a suitable spring-actuated valve 48, which is adapted to seat rearwardly against valve seat 49, in the direction of the supply chamber 41, so that a forward movement of the piston 30 will suck fluid into the. pump cylinder, whereas a backward movement of the piston will cause the fluid to close the valve 48. As shown in Fig, 3, the axial passage 47 before mentioned is connected by. means of a passage-50 with the interior der 38. Said passage 50 is controlled by means of a valve 51 which is spring-pressed, and is adapted to close against the seat 52 which is presented in the direction of the ram cylinder, so that when the pump piston 30 is moved rearwardly it will cause the charge of fluid in the pump cylinder to act to automatically open the valve 51 and to pass into the ram cylinder 38, therefore actuating the ram.

It will be seen that the pump and the jack .lie substantially horizontal when the platform of the truck is lowered, but. when power is applied to reciprocate the pump piston, the ram is moved so asto raise the platform, said platform being causedv to move in parallelism to itself or edgewise by reason of the action of the inclined members between the platform; and base. A careful operator of the hand lever would probably know when the-platform is sufli-fl ciently raised, but the ordinary or careless-I.

operator might not. To provide against injury to the mechanism, a control device is installed which is adapted to stop the action inclined with respect of the ram cylin-' of the jack automatically when the platfor is raised to'the proper height, and wh may be suitably actuated.

The referred control device menticfla is fully s own in Figs. 3 and 4. It comprises a valve 53 located in such position between passages 54,55, inthe:- head 37 as to control said passages. Said valve is normally retracted by a spring 56 which seats the same against a valve seat 57 which is formed in the small valve chamber 58 in a plug 59, which is screwed into a screw-threaded opening 60 in the-head 37, and which opening is to the longitudinal axis of the pump. The passage 54 leads from the interior ofthe ram cylinder 38 to the valve'chamber 58, leads from a chamber .59 to the chamber 41 around the jack. It will be seen that the said valve 53 which constitutes a relief valve is forced against its seat by the pumping and the passage 55 plug 61, into which recess the, adjacent end of the stem of valve '53 extends, but the said adjacent endsare normally separated by a space. Said chamber '59 is formed by, leav ing a space between the two plugs 59 and 61, and said chamber 59 communicates with valve chamber 58 by means of a port 59 controlled by valve 53. It will be seen that if at any time the plunger 62 is pressed inwardly against the stem of valve 53, the latter will be moved'away from its seat so as to open the port 59".

The retaining plug 61 of the control device and the plug 59 carrying the valve 53, beingarranged upon the outer peripheral wall of the common head between the pump and jack, constitute freely accessible means, the removal of which enables free access to the said valve whenever desired, as access to them is not hindered by any obstructing exterior parts. This feature of accessibility is also true as to the valves 48 and 51, inasmuch as screw plugs "48* and 51' are screwed into the outer peripheral wall of the common head so as to hold thevalves in place and render them accessible' Preferably the plugs 61, 48? and 51 in order to dispose them ina more convenient position for removal and insertion, extend away from the main axis of the commonhead, and the screw sockets for receiving said plugs are of course likewise disposed.

Suitable means may be proyided for actuating the plunger 62 of the described control device, such for instance as shown in Figs. 1 and 8. To this end a rock shaft 65 is jourthe pumped fluid will be forced into said chamber 41. This will automatically shut naled in suitable bearings 66 located uponthe front portion of the base of the truck,

and said rock-shaft carries a tappet or actuator 67. Said tappet or actuator is located in such position with respect to the plunger 62 of the control device that it is adapted to press on and operate said plunger. An arm 68 is mounted on rock-shaft 65 and is pivotally connected with a rod 69 which extends rearwardly of the truck and is loosely connected with the platform at 70.

It will be seen that by means of the said rod 69 which is moved b the-platform as the,

same is raised and s ifted rearwardly, the

off the action of the intermittently actuated mechanism or jack, and prevent the platform from being raised any higher.

Fig. 1 may be used, but the action is not; automatic.- To. this end there is connected.

AS an alternative means for operating the actuator 67 and as means for releasing the jack, the manually operated means-shown-in I with a' rock-arm 71Jqn the shaft 65 a link 72 which extends forwardly and is pivotally connected with a foot-piece 7 3 which is'pivfied, without 'departingfromthe invention as claimed'. For instance, the truck may be motor'propelled, and the elevating mechanism cou'ld'then be operated by the-sameor' oted to the base at 74. Said foot-piece is maintained in its normal raised position by means of a spring,- not shown. .It will beseen that by pressing down upon the footpiece 73, the actuator 67 may be operated whenever desired thus opening the connection between the cylinder 38 and the cham-.

ber .41 and permitting the platformto descend. Y

It is obvious that the described invention is susceptible of modification, as parts may;

be omitted, parts added," and parts modi by a separate motor.

' What I claim as new'is:'-

acyli-nder, a pump, a reservoir,said jack, pump and reservoir being -.so connected that saidpump'may. draw flu d from said reservoir and force it into: said cylinder behind said ram, and said structure being provided also with a passage leading through the wall 1;In a structure of'theclass 'described,a fluid-operated jack comprising a ram andi of said cylinder upon the pressure side of said ram to said reservoir, a valve in said passage, and means for. automatically controlling said valve to prevent over-extension of said jack.

2. In a structure of-the class described, a fluid-operated jack comprising'a ram and a cylinder, a pump, a reservoir, said jack,

pump andreservoi rbeing, so connected that said pump may draw fluid from said reser voir and force it into said cylinder behind said ram, and saidjstruct'ure being provided also with a passage leading. through the wall of said cylinder upon the pressure side of said ram to said reservoir, a valve in said passage, andmeaiis for automatically controlling said valve to prevent over-extension of said jack, said. valve being also constructed and arranged for operation at the will of the operator to releasesaid jack.

3. In a device of the class described, the combination of affluid operated jack comprising a ram anda cylinder, a reservoir, a pump provided with a head between it and said pump andjackbein jalined, and said jack, pump and reservoir eing so connected that said pump maydraw fluid from said reservoir and force it into said cylinder behind said ram, and said head being provided with a passage leading through the wall of said cylinder uponthe pressure side of said ram to said reservoir, a valve in said passage, and means for autdinatically controlling said 4. In a device of the class described, the combination of a" fluid operated jack comprising a ram and a cylinder, a pump, a

.reservoir, valved n'lieans for connecting said jack, pump andres'ervoir so that said pump may draw fluid from said reservoir. and force it into said eylinder at a pointbehind .said ram, said valved means being provided also with a passage leading from the? pres- 9 sure side of said-"ram, through the wall of said jack, and'in common with said jack, 1

"valveto prevent Qver extension of said jack.

said cylinder to said reservoir, a stem-valve insaid passage, a" spring for closing said valve, a. guide-infadvance of saidvalve, a spring-retracted "plunger- I uided in said guide r and substantially a me with and' spaced away from said stein,- plunger extending forwardly toward, the outer end of said pump awa from said jack, and

means to .acton plunger, wherebyf said.

plunger may be thrust against said stem to open its valve. l

v Signed at Holyoke, Mass, this 19th day of June, 1914. j

. DANIEL E. HENNESSY.

,Witnesses:

" ARTHUR L. Lnwis,

' R. T. LYON. 

